From 1996 to 2013, 4,555 cases of human anaplasmosis (HA) (formerly known as human granulocytic ehrlichiosis) were reported in Minnesota. In 2013, 627 confirmed or probable anaplasmosis cases (11.7 cases per 100,000 population) were reported. This represents a 24% increase from the 507 cases in 2012, although it is considerably lower than the record 788 cases in 2011. Despite these fluctuations, the trend is an increase in yearly case totals over time.
The number of anaplasmosis cases has been increasing since the first cases of HA were reported in Minnesota in the mid-1990s. A variety of factors, including increasing physician awareness, increasing infection rates in ticks, and expanding tick distribution, may have led to this trend.
The HA cases in 2013 ranged in age from 2 to 93 years; the median age (56 years) was greater than that of Lyme disease (42 years). In 2013, 63% of HA cases were male.
- Reported Cases of Human Anaplasmosis in Minnesota
by Year, 1996-2013 (PDF: 104KB/1 page)
Graph showing the number of reported cases of human anaplasmosis in Minnesota by year.
- Reported Cases of Human Anaplasmosis in Minnesota by Month of Onset 2000-2013 (PDF: 80KB/1 page)
This bar graph shows reported cases of Human Anaplasmosis by the month of onset.
Most HA cases report likely exposure to blacklegged ticks in the same east-central and north-central Minnesota counties where the risk of Lyme disease is greatest.
- High Risk Areas for Tick-borne Diseases in Minnesota
A map that shows counties of highest tick-borne disease risk in Minnesota.
- Anaplasmosis, 2012
Minnesota Department of Health, Disease Control Newsletter;
Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2012.